Tail suspension test (TST), which is invented by Steru et al. in 1985, is used for determining whether a mouse has melancholia or depression. The test is to suspend the tail of the mouse and then detect the agitation and immobility times of the mouse in a specific time (6 minutes in general). Many studies have proven that the immobility time of the depressed mouse is longer, since the depressed mouse is easily disappointed and gives up struggling. Such situation can be improved by treating the mouse with antidepressant drugs. Therefore, TST is a common method for screening antidepressant drugs, so as to develop new antidepressant drugs.
The advantage of TST is easy to perform, but the disadvantage thereof is that it is hard to define by naked eyes whether the action is agitation or immobility for those small actions between agitation and immobility, so that the variation and error of the experiments increase. To overcome this problem, Steru et al. used a digital-tension meter in 1987 to detect the struggling force of the mouse in each time point and connect to a computer to form an automatic detector (ITEMATIC-TST). However, such detector can only detect the tension change in the vertical direction but cannot detect the swing action in the horizontal direction, so that it is not widely used. In 1992, a Japanese named Nomura S used photoelectric elements and a microangular potentiometer to detect the struggling of the mouse, and then convert the predetermined analog potential signals into digital signals. However, such apparatus is complicated and inconvenient to operate, and many actions of the mouse cannot be detected; besides, it is too expensive, so this apparatus has not been used in any published paper. Thus, at present, when using TST to evaluate the melancholia or depressive symptom of the mouse, it is still observed by naked eyes and counted time by hand, which causes error easily.
Therefore, the present invention provides a TST apparatus which overcomes the above-mentioned disadvantages.